1. Field of the Invention
The present invention relates to a method of dyeing or reforming a surface of a plastic injection molding, including an injection compression or injection press molding, blow molding or compression molding; more specifically, this inventions relates to a method of dyeing or reforming a molding surface inside a mold for injection, blow or compression molding.
2. Description of the Related Art
In a method of coating with paint or reformer to dye or reform the plastic molding surface, there exist problems in terms of anti-wearing characteristic, cost and the like; and when this coating is applied, there are concerns about a work environment as well as an environmental problem which occurs after the molding becomes a waste, because an organic solvent is used in general.
Therefore there has been a request for technological proposals for dyeing or reforming the molding surface without using the organic solvent; at present the following technologies are disclosed, though there are only a few of them.
Japanese Patent Laid-Open Publication No. 2001-226884 (Patent Document 1)
Patent Document 1 is directed to a non-aqueous dyeing method for such materials as a resin molding, rubber molding and fiber, with a dye conducted in supercritical carbon dioxide; and this invention relates to, in the non-aqueous method of dyeing a material in the supercritical carbon dioxide, a dyeing method with supercritical dye liquor made from supercritical carbon dioxide and co-solvent thereof; and a dyeing material is any one of the resin molding, rubber molding or fiber. The co-solvent of the supercritical carbon dioxide is compound liquid mixed with one or more than one kind of water or polar organic solvent; the amount of the co-solvent accounts for 0.01˜10% of the supercritical carbon dioxide. The invention relates to a non-aqueous dyeing method of dyeing in the compound liquid of water, polar organic solvent alcohol or dimethylformamido, mixed with the supercritical carbon dioxide. This invention, however, is used with an autoclave for dyeing, therefore it takes time to carry a material to be treated into or out of the autoclave. Because the autoclave consumes a large amount of dye, it leads to a waste of money; also it is necessary to keep the autoclave at high pressures and high temperatures, which results in a large amount of energy consumption.
Japanese Patent Laid-Open Publication No. H6-081277 (Patent Document 2)
Patent Document 2 relates to a method which doesn't involve such troublesome work as creating vacuum atmosphere; in which it is possible to dye on both sides of chromatic optical components, and it is possible to dye at high concentrations over the relatively low heating temperature during a short period of time; and the invention relates to a method in which optical components stained with mixed color can be easily manufactured; and in which optical components and powdery resin dyeing agents are heated with both of which contacted with each other; the optical components and the powdery resin dyeing agents are placed inside a closed vessel to enable homogeneous contact between the optical components and the resin dyeing agents; and a method of heating and dyeing while adding such motion as rotation.
However, in this method the dyeing agents don't permeate into the dyed components, but dyeing layers are only formed on the surface; therefore it is unsuitable for a molding on which such problems as peeling may occur or friction is likely to develop.
Published Japanese translations of PCT international patent publication No. H 8-506612 (Patent Document 3)
Patent Document 3 provides a method of impregnating a various kinds of polymer carriers with impregnant, and a method of simultaneously contacting the polymer carriers, impregnant, carrier liquid and supercritical fluid. The impregnant is practically insoluble in the supercritical fluid, and favorably, a carrier body is practically insoluble in the supercritical fluid.
However, this invention uses liquid as a carrier; this liquid is supercritical carbon dioxide; and an autoclave is used. An untreated material is impregnated in the carrier mixed with additives inside the autoclave; and just like the case of Patent Document 1, a large amount of additive is likely to be consumed. The invention also consumes a large quantity of energy in order to keep the autoclave at high pressures and high temperatures.